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    K3S

    🪶 K3S Cheat-Sheet

    K3S is a lightweight Kubernetes distribution designed for IoT and edge computing environments. It’s production-ready and easy to install with a binary size under 100 MB, consuming less memory compared to traditional Kubernetes setups.

    🔍 Overview

    • Product Type: Lightweight Kubernetes Distribution

    • Focus: K3S is tailored for environments that need a small footprint and minimal resource consumption, such as IoT, edge computing, and small clusters.

      • Single-Node Setup: Ideal for development and testing

      • Multi-Node Setup: High Availability (HA) configurations with embedded or external databases

      • Ease of Installation: Simple and quick installation with automated scripts

    🔧 Installation

    You can install K3S using several methods: with an external database, embedded database, or as a single-node setup.

    📊 K3s with External DB

    Set up a High Availability (HA) K3s cluster backed by an external database like MySQL, PostgreSQL, or etcd.

    🗃️ Install Database

    • First, install MariaDB or your preferred database.

    🖥️ Install Servers

    To install K3s with an external database:

    curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--datastore-endpoint='mysql://user:pass@tcp(ipaddress:3306)/dbname' \
--node-taint CriticalAddonsOnly=true:NoExecute \
--tls-san your-dns-name --tls-san your-lb-ip-address

    [!info]
    The --node-taint flag ensures that your server node won’t run workloads, only the control plane.

    🔒 SSL Certificates

    To avoid certificate errors, you should use the --tls-san YOUR_IP_OR_HOSTNAME_HERE option to add extra IPs or hostnames to the TLS certificate.

    🚀 Install Agents

    You can install agents on additional nodes:

    curl -sfL https://get.k3s.io | sh -s - agent \
--server https://your-lb-ip-address:6443 \
--token YOUR-SECRET

    💾 K3s with Embedded DB

    Set up an HA K3s cluster using K3s's built-in distributed database (etcd).

    🖥️ Install the First Server

    curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--tls-san your-dns-name --tls-san your-lb-ip-address \
--cluster-init

    [!tip]
    The --tls-san option ensures no SSL certificate errors when accessing the server via IP or hostname.

    🏗️ Install Additional Servers

    To add more servers:

    curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--tls-san your-dns-name --tls-san your-lb-ip-address \
--server https://IP-OF-THE-FIRST-SERVER:6443

    The --cluster-init option initializes the HA cluster with an embedded etcd database. You need at least 3 nodes for fault tolerance.

    🗓️ Fault Tolerance Table

    Total Number of NodesFailed Node Tolerance
    10
    20
    31
    41
    52
    62

    🖥️ Install Agents

    To install agent nodes:

    curl -sfL https://get.k3s.io | sh -s - agent \
--server https://your-lb-ip-address:6443 \
--token YOUR-SECRET

    ⚙️ K3s Single Node

    Set up K3s as a single-node installation.

    [!warning]
    This setup is ideal for testing and development but may not be suitable for production.

    🛠️ Manage K3S

    💻 Management on Server Nodes

    Use the K3S-specific kubectl to manage your cluster:

    k3s kubectl

    📜 Download Kube Config

    You can download the kubeconfig file from:

    /etc/rancher/k3s/k3s.yaml

    💾 Database Backups

    🧳 etcd Snapshots

    K3S stores etcd snapshots in the following directory:

    /var/lib/rancher/k3s/server/db/snapshots

    [!tip]
    Regular backups of the etcd database are crucial for disaster recovery.

    📚 Resources

    🌍 Explore More

    Tags 📚

    #k3s #kubernetes #cluster #high-availability #lightweight #edge-computing

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